The present invention relates to fuel tanks for small engines such as those employed in portable power equipment as, for example, lawn mowers and portable generator sets. Recent regulations for controlling the emission of fuel vapors have required installation of vapor storage devices to prevent escape of fuel vapors through the engine air inlet during periods when the engine is not operating and provide for purging when the engine is running. This recently imposed requirement on small engine manufacturers has created problems in installing the engines in the equipment in which they are to be used inasmuch as the equipment manufacturer commonly purchases the engine and fuel tank for installation as a subassembly during final assembly of the engine operated equipment. Thus, for the aforesaid equipment applications the burden of providing for fuel vapor emission control has been imposed upon the small engine manufacturer and has created problems in the design and installation of the tank and fuel system for the small engines.
In particular, the requirement for a vapor storage device has been found to create problems in mounting the tank and fuel system on a small engine as a prepackaged subassembly; and, has added additional costs in providing for the storage device and the mounting and vapor conduit interconnections between the storage device and the tank. Thus, it has been desired to provide a way or means of controlling fuel vapor emissions from a small engine tank installation in a manner which is self-contained and low in cost.